The present invention relates to a clutch unit which has the function of transmitting input torque from an input side to an output side and locking reverse input torque from the output side so as not to flow back to the input side, and is applicable to a seat-adjusting device of a vehicle, for example.
For example, for a device in which an input torque given by a rotating operation of an operation member is transmitted to an output-side mechanism to adjust a position of a predetermined part, a function for holding the position of the output-side mechanism is often required when the operation member is not operated. Taking a seat-height-adjusting device for a sitting seat of a vehicle, for example, the device comprises a brake part for supporting the weight from the sitting seat including the weight of the seat itself and the weight of the driver and the like, provided at an output-side mechanism, wherein a normal or a reverse input torque is input from an operation member to an input shaft of the brake part to adjust the height position of the sitting seat. The height position of the sitting seat is held by the brake part even when the operation member is released. Thus, the above function is performed. In this case, since the position of the operation member is held by the brake part after the operation, a knob (or a circular grip) is commonly used as the operation member, and the input torque is input to the brake unit by the rotating operation of the knob.
The seat-height-adjusting device of the prior art requires inconvenient operation of rotating the knob while the driver inserts his hand in a narrow space between the sitting seat and the vehicle body. Also, the necessity to secure such space imposes limits to the design of the vehicle body and the seat, which can be a burden particularly for small vehicles. Another known seat-height-adjusting device employs a lever as the operation member, with a ratchet mechanism between the lever and the brake part so as to enable to input a torque by a pivoting operation of the lever and to automatically return the lever after operation. However, this device requires a complex structure, and also has the problem of noise generated by toothed ratchet gears when the lever returns.